This study evaluates the decentralization of workers' health surveillance to district teams in Campinas, São Paulo State, Brazil, from 1990 to 2006. The history and context of this process were retrieved from documents at the Municipal Health Department in order to establish evaluation criteria and define facilitating factors and obstacles in guideline implementation, as well as to measure the gap between guidelines and reality. The evaluation used qualitative techniques with stakeholders' focus groups. The results showed that decentralization was defined according to the prevailing political options and according to the principles of the Unified National Health System (SUS). Facilitating factors included the increase in technical capability and integration among the teams, and obstacles included excessively centralized planning with limited participation, insufficient resources, and lack of clarity between the services concerning roles and responsibilities. The discussion of these results with health system administrators, social actors, and participating health professionals has contributed to the analysis and organization of transformative measures in regional public practices in workers' health surveillance.